Clamping frame for vacuum forming parts



Jan.- 17, 1961 G. H. HOWELL CLAMPING FRAME FOR VACUUM FORMING PARTS Filed June 24, 1959 '5 sheets-sheet 1 I GEORGE H HOWELL BY ,ayu l( W- Ummm ATTORNEY Jan. 17, 1961 G. H. HOWELL 6 CLAMPING FRAME FOR VACUUM FORMING PARTS Filed June 24, 1959 5 Sheets-Sheet 2 76 INVENTOR GEORGE H HWELL BY W avia/@6W ATTORNEYv United States Patent() CLAMPING FRAIVIE FOR VACUUM FRMINGf PARTS 5 Filed June 24, 1959, SenNo. 822,669 9 claims. (ci: '18;19')

rIhis` invention relates to plastcmoldingapparat-usand. more particularly to a drape traine structure employedixr such apparatus.

Drape plastic molding has recently become widely utilized. This method of molding is accomplished by heating a plastic sheet to a soft pliable state andk then draping the sheet over a forming die. A frame is generally used to hold the sheet of plastic in a horizontal position above the die While being heated. Diiculties have been encountered in obtaining quality products when draping the plastic sheet over dies with complex shapes.

It is an object of'this invention to provide a new-frame and die structure which facilitates frame and die alignment so that the plastic sheet may be draped uniformly. about irregular die forms.

A further object of this invention is to provide a drape frame and die `structure having an improved sealing engagement between the frame and die in the molding position. Other objects and advantages will become apparent from the following detailed description wherein reference is made to the accompanying drawings in which:

Figure 1 is a perspective View of the principal elements of the invention,

Figure 2 is an elevational view, partly in cross section, of the principal elements shown in Figure l,

Figure 3 `is a cross sectional view of the molding apparatus of Figure 1 in molding position,

Figure 4 is a perspectiveview of the molding elements of Figure 1 combined with special operating apparatus, and

Figure 5 is a perspective View of the apparatus of Figure 4 in molding position.

As shown in Figure 1 my invention consists of a die holder which comprises a base portion 12 and a pair of upwardly extending end walls 14, 16 oppositelyl positioned on the base. The end Walls 14 and 16 define a cavity 18 therebetween. The side surfaces 2llof the end walls are inclined to the plane of the base and. terminate at their upper ends in substantially parallel ridges 22 and 24. The sloping side surfaces 20 of the end walls and the outer periphery of the base section may be formed integral to provide a common facing or ledge 26'extending laround the entire periphery of the die holder.

In the preferred embodiment, a pair of dies 2S, 30 are secured within the cavity 18 between the end walls 14, 16. A single die could be positioned in the cavity, but in this instance a pair of crash pad dies are secured therein and separated by a tension bar 32 having a. contoured top surface adapted to support andstress the molding material during the forming operation.

Referring now to Figure 2, a support frame 34 having a central aperture 36 (Fig. 1) is provided with an inner peripheral side edge 38. The inner peripheral dimension of the frame 34 as dened by the edge 38 is greater than the outer peripheral dimension of the dieholder 1'0. The outer peripheral side edge 40 ofthe support frame may be spaced any suitable distance from the inner peripheral side edge 35 to provide a seating portion. 42 around theinnenpeipheryof the substantiallysat upper surface. of thesupport frame. In this illustration aseaLhavinga of-about one inch is preferred.v The upper surface of-.the support frame may be at, as shown in Figure 1,. orhave a raised outer edge, asshown in yFigure 2. Y v

An apertured h`oldingvframe46 for a plastic sheet 4? isformedby aA space enclosingrirn with an outer peripheralV edge 50. of` larger. dimensionfthan the-inner peripheral ,.edge.38foffthe rinfoffthel support frame34; The inner` peripheral-.edgeSZ-of tlieaholdingframe 46 is` suitably-l dimensionedl'sol that aseat 54 is providedA around the outer periphery of its bottom surface. The seat 54Vis about one inchin width'so as to correspond to the seating portion 42 on thetupper surface of the support frame 34; A plurality of vacuum ports 56 opening onto the sheet 48 are inwardly spaced vfrom the seat 54 around Ithe innerperiphery of the. bottom surface of the holding frame and connected by an internal passage 58to vacuumap-` paratus (not shown). It is understood that meansV other than vacuum. ports may be utilized for securing the plastic sheet to the holding frame.

As illustrated inFigures 1 and 3, a pair ofhingest), 62 pivotably connect adjacent portions ofV the frame 46 at opposite points. onA the frame and thus divide the` frame into foldable sections. The adjacent portions may` be substantiallyv U-shaped. The vacuum portsY S6 in ther frame are connected at thesepointsby means ofvacuum hoses 64 and 66. The bottom, surface of the frame is coextensive with andcontoured to engage the facing 26 of the die holder 10. The plastic sheet 48 is securely held around the inner periphery of the holding frame? 46 by vacuum in the ports 56. A work table may be used to support the die holder 10. In the molding positionof Figure 3, the holding frame 46 is sealingly engagedaround `the facing 26v ofthe die holder 10. A vacuum port 70 is associated with the die members 28- and 30" withinthe cavity 18, and through vacuum pressure lineA 72 is connected to suitable vacuum apparatus (not shown).

Figures 4 and 5 show the embodiment of Figure 1 asv utilized with special forming apparatus. A die table 74 is provided with a at workingV surface 76in .which is located a vacuum port 78. A flat support platform' 80` is shown, in Fig. 4, inclined to theworkingsurface 76: Aplurality of rollers 82 or other translation meansare secured to one edge of the support platform to support the platform on the table. The opposite edge of `theT support platform is connected by hinges 84 to the holdingl frame 46. A three sided support frame 86 guides'the holding frame into engagement with :the-die'holder. The die'holder 10 is securely. fastened to the support platform' intermediate the opposite edges of the support platform, and a vacuum port 88 extends Ithrough the support plat# form to cooperate with the port 78.

In operationrof the= apparatus shown in Figure l, a' plastic sheet `48 is positioned and held between the hold-- ing frame 46 and the support frame 34. The plast-ic sheet 48 after positioning is heatedto` a pliable state. When the plastic sheetis sufficiently heated, the support frame is lowered/over the ydie holder or the die holder is raised so that the hinges 6,0 and 62 are positioned in corresponding relation to theV substantially parallel ridges" 22, 24 on the die holder 10. As the support frame 34-isf lowered aroundV the diek holder 10, the rid-ges 22, 24`

frame aperture 36 and the holding frame is then supported in sealing engagement with the die holder. A vacuum is created within the cavity 18 so that the plastic sheet is drawn down and around the dies. The tension bar 32 serves to maintain a strain on the sheet to avoid wrinkling of the material during forming.

The special apparatus shown in Figs. 4 and 5 holds the plastic sheet 48 in a heating position just above the die holder in the inclined position of the support platform 80. When the plastic sheet is sufficiently heated, the support platform is moved from the heating position of Figure 4 to the forming position of Figure 5 by lateral movement on the rollers 82, actuated by the vertical movement of either the support frame 86 or the die table 74. This movement brings the support platform into substantially parallel alignment with the working surface 76 of the die table 74 and simultaneously lowers the support frame 86 over the die holder 1,0 to fold the holding frame 46 into engagement with the facing 26 as shown in Figure 5. The vacuum port 78 is aligned with the port 88 in the die holder at the forming position.

Thus, it is apparent that I have provided a new and useful means of drape molding wherein the alignment of a heated plastic sheet and its subsequent vacuum molding is more readily accomplished.

I claim:

1. A support for moldable plastic materials comprising an apertured frame formed by a pair of substantially U-shaped rim members, hinge means connecting said rim members at their open end to provide a substantially continuous rim foldable about said hinge means, said rim having a substantially at bottom surface, a seat formed by the outer peripheral portion of said bottom surface, holding means for a sheet of plastic material spaced inwardly from said seat and around the entire inner peripheral portion of said bottom surface, and said holding means being operatively associated with said sheet in all positions of said foldable rim.

2. A support for moldable materials as defined by claim l wherein said holding means comprises a plurality of vacuum ports in said rim members opening through said bottom surface, a passage in each of said members interconnecting said vacuum ports, and flexible hose means interconnecting the passage in one member with the passage in the other member.

3. Molding apparatus comprising in combination a die holder having a base section, a frame supporting ledge formed around said base section by the peripheral facing of said die holder, opposite peripheral portions of said die holder extending upwardly from said base section to form a die retaining cavity therebetween, the side surfaces of said upwardly extending peripheral portions of said die holder that form part of said peripheral facing being inclined to the base and terminating in substantially parallel ridges, forming means in said cavity; a holding frame for plastic molding material having a surface coextensive with and adapted to engage said supporting ledge of said die holder, said frame having a plurality of sections, means to secure moldable material to said frame sections inwardly adjacent said frame surface, and hinge means connecting said sections along said frame surface at points corresponding to said parallel ridges of said die holder whereby said frame may be folded about said pivotal hinge means to engage said frame surface with said ledge of said die holder and thereby position said moldable material adjacent said die.

4. Molding apparatus comprising the combination of a die holder having a base and a pair of opposite upwardly extending end walls defining a die receiving cavity therebetween, `the edges of each end wall being inclined to said base and terminating in parallel ridges, a continuous facing formed by the edges of said end walls and the edges of said base; die means in said cavity between said end walls and below said ridges, vacuum forming means associated with said die means in said cavity; a

rigid apertured support member having an inner periph eral dimension larger than the outer peripheral dimension of said die holder to allow said support member to be lowered therearound; a frame comprising a rim co-extensive with and contoured for engagement with said facing of said die holder, a seat formed on the outer periphery of said rim and having an outer peripheral dimension greater than the inner peripheral dimension of said support member to hold said frame on said support member, means for holding moldable material around the inner periphery of said rim, and hinge means connecting portions of said rim at points on said rim corresponding to the points on said facing of said die holder where said parallel ridges are located whereby said frame is folded into engagement with said facing as said support member is lowered around said die holder.

5. Molding apparatus comprising in combination a die table having a horizontal working surface, a vacuum port on said surface; a flat support platform movable from a first position inclined to said working surface to a second position parallel to and closely adjacent said working surface, rolling means spaced along one edge of said platform and supporting said platform on said working surface; a die holder carried by said platform and having a base section, a frame engaging ledge formed around said base section by the peripheral facing of said die holder, opposite peripheral portions of said die holder extending upwardly from said base section to form a die retaining cavity therebetween, the side surfaces of said upwardly extending peripheral portions that form a portion of said peripheral facing being inclined to the base and terminating in substantially parallel ridges, forming means in said cavity connected with said vacuum port when said platform is in said second position; a support frame comprising a space enclosing rim, hinge means connecting one edge of said support frame to an edge of said platform opposite said rolling means, the inner peripheral dimension of said support frame being greater than the outer peripheral dimension of said die holder to allow said die holder to pass through said support frame as said platform moves from said first to said second position; a holding frame for plastic material formed by a rim co-extensive with and contoured for engagement with said ledge of said die holder, a seat formed on the outer periphery of said rim and having an outer peripheral dimension greater than the inner peripheral dimension of said support frame for supporting engagement therewith, means for holding moldable material around the inner periphery of said rim, and hinge means connecting portions of said rim of said holding frame at points corresponding to the points on said facing of said die holder where said ridges are located whereby said holding frame may be folded into engagement with said facing as said platform moves from said first to said second position.

6. Molding apparatus comprising in combination a die holder having a base section, said die holder having a continuous peripheral facing extending upwardly from said base section to form a die retaining cavity, portions of said peripheral facing being inclined to one another; a holding frame for plastic material having a surface coextensive with and contoured for engagement with said peripheral facing of said die holder, said frame comprising a plurality of sections, and flexible means interconnecting adjacent sections along said surface to permit relative movement between sections whereby said frame surface may be moved into engagement with said peripheral facing and thereby position said plastic material adjacent said die.

7. Molding apparatus comprising in combination a die holder having a base section and a continuous peripheral facing extending upwardly therefrom to form a die retaining cavity, portions of said peripheral facing being inclined to one another; vacuum forming means associated with said die means in said cavity; a holding frame for plastic material having a surface coextensive with and contoured for sealing engagement with said peripheral facing of said die holder; means for holding said plastic material around the entire inner periphery of said surface including a plurality of vacuum ports opening through said surface, said frame comprising a plurality of sections, and flexible means interconnecting adjacent sections along said surface to permit relative movement between sections whereby said frame surface may be moved into sealing engagement with said peripheral facing.

8. Molding apparatus comprising in combination a die table having a horizontal working surface, a vacuum port on said surface; a flat support platform movable from a rst position inclined to said working surface to a second position parallel to and closely adjacent said working surface, rolling means spaced along one edge of said platform and supporting said platform on said working surface; a die holder having a base section and a continuous peripheral facing extending upwardly from said base section to form a die retaining cavity, portions of said peripheral facing being inclined to one another; forming means in said cavity connected with said vacuum port when said platform is in said second position; a support frame comprising a space enclosing rim, hinge means connecting one edge of said support frame to an edge of said platform opposite said rolling means, the inner peripheral dimension of said support frame being greater than the outer peripheral dimension of said die holder to allow said die holder to pass through said support frame as said platform moves from said first to said second position; a holding frame for plastic material having a surface coextensive with and contoured for engagement with said peripheral facing of said die holder, a seat formed on the outer periphery of said surface and having an outer peripheral dimension greater than the inner peripheral dimension of said support frame for supporting engagement therewith, means for holding moldable material around the entire inner periphery of p said surface, said frame comprising a plurality of sections, and flexible means connecting adjacent sections along said surface to permit relative movement between sections whereby said holding frame surface may be moved into engagement with said facing as said platform moves from said first to said second position.

9. Ak holding apparatus comprising in combination a die table having a horizontal working surface, a vacuum port on said surface; a at support platform movable from a rst position inclined to said working surface to a second position parallel to and closely adjacent said working surface, rolling means spaced along one edge of said platform and supporting said platform on said working surface; a die holder having a base section and a die retaining cavity; forming means in said cavity connected with said vacuum port when said platform is in said second position; a support frame comprising a space enclosing rim, hinge means connecting one edge of said support frame to an edge of said platform; a holding frame for moldable material having an outer peripheral dimension greater than the inner peripheral dimension of said support frame, a seat formed about the outer periphery of said holding frame for supporting engagement with said support frame; means for holding moldable material around the inner periphery of said holding frame; and the inner peripheral dimension of said support frame being greater than the outer peripheral dimension of said die holder to allow said die holder to pass through said support frame to position said moldable material closely adjacent said die holder as said platform moves from said first to said second position.

References Cited in the file of this patent UNITED STATES PATENTS 2,081,777 Talalay May 25, 1937 2,189,006 Hutchinson Feb. 6, 1940 2,694,227 Fordyce et al. Nov. 16, 1954 UNITED STATES PATENT OFFICE CERTIFICATION OF CORRECTION Patent No-f, v 2,968,064 f January 17, 1961 George H.. Howell It is hereby Certifedthat error appears in the labove numbered patent requiring correction and that the said Letters Patent should read as corrected below Column 4, line 64, Column 5, line 7, yand column v,6, line 3, Tor flexible, each occurrence, read flexile m,

Signed and sealed this 27th day of June 1961.,y

(SEAL)v Attest: e

ERNEST W. SWIDER DAVID L. LADD Attesting Officer Commissioner of Patents 

